Racer Jessi Combs was attempting to hit speeds of over 600 miles per hour when her vehicle crashed, killing her in rural Oregon on Tuesday (Aug. 27). Police now say a fire was involved, and her boyfriend describes the accident as horrific.

Terry Madden was one of the first to share the news of the 39-year-old's tragic death while trying to beat her own land speed record on a dry lakebed in Oregon's Alvord Desert. In a lengthly Instagram caption that was posted next to a memorial video, Madden urges fans to patiently wait for details as released by the family and not to donate money to any cause, as he feels there will be people trying to make money off of Combs' accident.

"I have never loved or been loved by anyone as much as this amazing woman," he writes. "She was truly my unicorn and I enjoyed every single minute that I had with her. She was the most amazing spirit that I have ever or will ever know. Unfortunately we lost her yesterday in a horrific accident, I was the first one there and trust me we did everything humanly possible to save her!!"

Combs, who hosted shows like Overhaulin' and The List and appeared on Mythbusters, was surrounded by friends and family at the time of her death, per a statement from the family at Autoblog. There are few details, although the New York Post shares that investigators are hoping to obtain laptop computers onboard the North American Eagle Supersonic Speed Challenger so they can determine what went wrong.

A police official told the newspaper that "there was a fire involved," but did not elaborate.

The South Dakota native got the nickname of "fastest woman on four wheels" after piloting this vehicle to 398 mph in 2013 and then 483 mph five years later. Friends, fans and co-workers immediately took to social media to grieve and memorialize her properly. Adam Savage from Mythbusters, Chris Jacobs from Overhaul and Jay Leno are three notables who tweeted:

Combs' final two posts on Instagram are haunting in retrospect. The first (above) talks about how it may seem crazy to walk "directly into the line of fire." Her final post thanks everyone for their friendship and loyalty.

"I was the first one there and trust me we did everything humanly possible to save her," Madden shares. "I’m not ok, but she is right here keeping my going-I made her a promise that if this didn’t go well that I would make sure and do good with it, please help me with that."

He alludes to a documentary that was being filmed and will still be completed. He also shares that with Combs' family, they'll announce a proper foundation to donate to.